Spools for business machines

ABSTRACT

A spool for a business machine is provided on the hub with a prong for the attachment of a ribbon, such as an inked ribbon, to be wound on the spool, and with a projection, preferably on the hub itself, which prevents the prong from cracking, breaking or becoming permanently deformed under the hoop stress due to the wound ribbon. The prong also serves to reduce the risk of the prong being broken by the use, as is the habit of some operators, of a nail file or penknife or the like to facilitate the attachment of the ribbon to the prong.

Unite States Patent Payne Apr. 4, 1972 SPOOLS FOR-BUSINESS MACHINES Derek G. Payne, Sevenoaks, England Walter Grafton & Son Limited, London, England Filed: June 1,1970

Appl, No.: 42,046

Inventor:

Assignee:

Foreign Application Priority Data June 13, 1969 Great Britain ..30,042/69 References Cited UNITED STATES PATENTS 8/1964 Spradlin ..197/175 FOREIGN PATENTS OR APPLICATIONS 1,119,879 12/1961 Germany ..197/175 881,667 7/1953 Germany 197/175 958,113 5/1964 Great Britain ..197/175 Primary Examiner-Stanley N. Gilreath Assistant Examiner-Milton Gerstein Attorney-Larson, Taylor and Hinds 5 7 ABSTRACT A spool for a business machine is provided on the hub with a prong for the attachment of a ribbon, such as an inked ribbon, to be wound on the spool, and with a projection, preferably on the hub itself, which prevents the prong from cracking, breaking or becoming permanently deformed under the hoop stress due to the wound ribbon. The prong also serves to reduce the risk of the prong being broken by the use, as is the habit of some operators, of a nail file or penknife or the like to facilitate the attachment of the ribbon to the prong.

6 Claims, 10 Drawing Figures PATENTEDAPR 11972 SHEET 1 OF 2 FIGS.

PATENTEDAPR 4|972 3,653 605 sum 2 [IF 2 1 PIC-3.10. 6 18 SPOOLS FOR BUSINESS MACHINES This invention relates to spools for use in business machines, such as typewriters, adding machines, cash registers and computers, and is particularly concerned with the type of spool that is used for inked ribbon or carbon film ribbon and is provided with one or more prongs for the attachment of the ribbon. Such a prong may extend in cantilever fashion a little way over the surface of the spool hub, from its root which is on the hub, a gap being provided between the prong and hub. Alternatively the prong may be a projection on one edge of a window in the hub as shown in US. Pat. No. 3,092,349.

The prong is tapered to a point so as to pierce the end of the ribbon to secure it to the spool and the prong is usually barbed to prevent the ribbon coming off on reversing. A barbless prong may be provided when the spool is to be used with a tension operated reverse mechanism.

Where the spool is wholly or mainly formed by moulding, usually from plastics material, it is most convenient to mould the prong integrally with the hub. However, certain weaknesses have been found to arise when this is done. One weakness is due to the great pressure that is put on the prong when the ribbon is fully wound on the spool, this being particularly noticeable with modern nylon ribbons which are being increasingly used. There is a tendency for the prong to deform and for the tip of the prong to be left touching or nearly touching the hub, thus making it difficult or sometimes impossible to attach a new ribbon. In some cases it has been found that an incipient crack has been induced in the prong or that the prong has broken at the root.

Another weakness or disadvantage of an integrally moulded prong, as hitherto used, is that the unrestricted gap beneath the prong from the point to the root sometimes induces the operator, when attaching a new ribbon, to use a thin implement such as a nail file, penknife or scissors to push the ribbon under the prong to facilitate piercing. This practice occasionally leads to the prong being broken because it is accidentally levered upwards by the implement during ribbon attachment.

It is the primary object of the present invention to provide Spools in which the aforesaid weaknesses cannot arise during the ordinary use of the spools. A further object is, in the case of barbed prongs, to reduce the size of the barb that need be used for practical purposes.

According to the invention, a spool for a business machine is furnished with a prong moulded integrally with the spool hub and extending over a portion of the hub so as to provide a gap between the hub and prong, and with a projection in the gap to limit such deformation of the prong (under hoop stress resulting from the winding of ribbon over the prong) to such an extent as to avoid causing it to crack, break or become permanently deformed, the projection being so shaped as to permit the attachment of a ribbon to the prong. The projection preferably extends from the hub and is moulded integrally therewith.

The projection may conveniently be a pip or bar of any desired shape and is located beneath the prong in such a position that when pressure is applied at the radially outermost point on the prong, the underside of the prong bears on the support preventing the prong from deforming beyond its elastic limit, even over a long period of time. The radial height of the support can be such that it either just touches or just clears the underside of the prong before the ribbon is wound over the prong. In the former case the projection will not form an obstacle to pulling the ribbon on to the prong if the natural resilience of the plastics material from which the prong is moulded enables the prong to be lifted slightly to permit the passage of the ribbon. In the latter case, the clearance between the prong and projection can be restricted to that which, while allowing some small movement towards the projection, will not cause weakening at the root of the prong with the consequent chance of crack formation, but will still allow plenty of room for the piercing of the ribbon.

The projection has the further advantage that it eliminates, at least to a very considerable extent, the unrestricted gap beneath the prong, so that the operator cannot use in a destructive way a thin implement as aforesaid when piercing the ribbon.

In the case of a barbed prong, the projection, although formed on the hub, helps to prevent the ribbon from coming off the prong, thereby enabling the size of the barbs to be reduced.

In order that the invention may be clearly understood and readily carried into effect, a spool in accordance therewith will now be described, by way of example, with reference to the accompanying drawings, in which:

FIG. 1 is a plan of the spool;

FIG. 2 is an elevation of the spool of FIG. '1 as viewed in the direction of the arrow II in FIG. 1;

FIG. 3 is a plan of a detail, shown on an enlarged scale, of the spool of FIG. 1;

FIG. 4 is an elevation of the detail of FIG. 3;

FIGS. 5 and 6 are views similar to those of FIGS. 3 and 4 showing a modification;

FIGS. 7 and 8 are views similar to those of FIGS. 3 and 4 showing a further modification; and

FIGS. 9 and 10 are a plan and elevation of a portion of a further spool, shown on an enlarged scale.

The spool shown in the drawings is moulded in one piece from styrene-acrylo-nitrile and comprises a hub 1 between parallel flanges 2 each having an embossed outer ring 3 and embossed spokes 13 radiating from the inner portion 14 of the flange. The hub 1 is formed with axial driving holes 4 and, on its surface, with flats 5 extending the full distance between corresponding apertures 15 in the flanges. Mid-way between the flanges, the flats carry barbed prongs 6. As shown in FIG. 1, the prongs 6 point circumferentially in opposite directions, to facilitate the winding of the ribbon in either direction.

As shown in FIGS. 3 and 4, each prong 6 has a barbed tip 7 that projects 0.125 inch (dimension x) from a root 8, the total length (dimension x+y) of the prong being 0.25 inch. In the gap between the tip 7 and the base of the associated recess 5 is a projection 9, 0.037 inch high (dimension v) and 0.060 inch wide (dimension w). It has a roughly parabolic cross-section and this, coupled with the natural resilience of the tip 7 and the small initial clearance between the tip 7 and projection 9, enables the ribbon readily to be attached to the prong 6. The tip 7 can bend into contact with projection 9 under the hoop stress in the wound ribbon, but the projection 9 arrests the bending before the elastic limit of the prong is reached.

The arrangement shown in FIGS. 5 and 6 is similar to that of FIGS. 3 and 4 except that the tip 17 is a simple prong without any barb.

The projection 9 serves the further function of preventing an operator using an implement, such as a nail file, in a destructive way. The projection 9 limits the position of any such implement to a point where little or no damage can occur, for example as a result of levering the prong outwards at the root, whilst still allowing the tip of the prong to pierce the ribbon, if necessary under the action of an implement as aforesaid.

In the modification of FIGS. 7 and 8, two barbed prongs 6 project in opposite directions in cantilever fashion from a pedestal 10 that extends radially from the hub l, which also carries projections 9 beneath the prongs 6.

In the further modification of FIGS. 9 and 10, the hub l (the flanges of which are omitted from the drawing) is formed with a flat l8 and a shoulder 19 from which a barbed prong 6 projects over a projection 9 on the flat 18. The radially outer face of the prong 6 is faired into the cylindrical contour of the hub l and is made to conform as closely as possible to the curved surface of the hub so as to reduce indentations being made in the wound ribbon. As in the other examples, the hub, prong and projection are moulded in one piece from thermo-plastic plastics material.

I claim:

1. A spool for a business machine comprising:

a moulded spool hub,

at least one prong mounted integrally with the spool hub, said prong extending circumferentially over a portion of the hub from a root forwardly to a point and spaced from the hub to define a gap between the prong and the hub, and

a means for limiting deformation of the prong towards the hub under hoop stress resulting from the winding of a ribbon on the hub over the prong, while concurrently permitting attachment of a ribbon onto the prong,

said means comprising a projection on the hub in said gap,

said projection being located, circumferentially, rearwardly of the said point of the prong, providing the full amount of said gap between the hub and the prong beneath the point of the prong, whereby the ribbon can be moved onto said point of the prong without interference from the projection, and

said projection extending up from the hub to a first height, the said prong being elastically deformable between said first height and a second height farther from the hub than the first height, the distance between said first and second heights being sufficiently large to enable the end of a ribbon attached to the said point to pass between the prong and the projection to attach the ribbon to the prong.

2. A spool according to claim 1, wherein the projection is moulded integrally with the hub.

3. A spool according to claim 1, wherein the projection narrows upwardly, and wherein the base of the projection at the hub surface is adjacent the said root of the prong, whereby the space between the root and the projection is sufiiciently small to prevent a thin implement, when used to push the ribbon under the prong to facilitate piercing, from being manipulated in such a way as to break the prong.

4. A spool according to claim 1 including two similar prongs, each with a said projection to limit its deformation, the prongs pointing circumferentially with respect to the hub in opposite directions, to facilitate winding the ribbon on the spool in either direction.

5. A spool according to claim 4 including a pedestal on the hub, from which the prongs project at opposite directions.

6. A spool according to claim 1 including a shoulder on the hub, the outer surface of the prong substantially conforming to the outer surface of the shoulder at the location where the prong projects circumferentially from the shoulder, so as to reduce indentations made in the ribbon when wound on the hub over the prong. 

1. A spool for a business machine comprising: a moulded spool hub, at least one prong mounted integrally with the spool hub, said prong extending circumferentially over a portion of the hub from a root forwardly to a point and spaced from the hub to define a gap between the prong and the hub, and a means for limiting deformation of the prong towards the hub under hoop stress resulting from the winding of a ribbon on the hub over the prong, while concurrently permitting attachment of a ribbon onto the prong, said means comprising a projection on the hub in said gap, said projection being located, circumferentially, rearwardly of the said point of the prong, providing the full amount of said gap between the hub and the prong beneath the point of the prong, whereby the ribbon can be moved onto said point of the prong without interference from the projection, and said projection extending up from the hub to a first height, the said prong being elastically deformable between said first height and a second height farther from the hub than the first height, the distance between said first and second heights being sufficiently large to enable the end of a ribbon attached to the said point to pass between the prong and the projection to attach the ribbon to the prong.
 2. A spool according to claim 1, wherein the projection is moulded integrally with the hub.
 3. A spool according to claim 1, wherein the projection narrows upwardly, and wherein the base of the projection at the hub surface is adjacent the said root of the prong, whereby the space between the root and the projection is sufficiently small to prevent a thin implement, when used to push the ribbon under the prong to facilitate piercing, from being manipulated in such a way as to break the prong.
 4. A spool according to claim 1 including two similar prongs, each with a said projection to limit its deformation, the prongs pointing circumferentially with respect to the hub in opposite directions, to facilitate winding the ribbon on the spool in either direction.
 5. A spool according to claim 4 including a pedestal on the hub, from which the prongs project at opposite directions.
 6. A spool according to claim 1 including a shoulder on the hub, the outer surface of the prong substantially conforming to the outer surface of the shoulder at the location where the prong projects circumferentially from the shoulder, so as to reduce indentations made in the ribbon when wound on the hub over the prong. 